To provide a work machine for a printed board capable of work at a high speed for a small diametric hole, by suppressing a vibration generated by movement in a spindle part.

In this work machine for a printed board, relatively moving a table 4 loading the printed board and a cross slide 9 arranged in the upward of the table 4 in a direction XY also moving a spindle part supported to the cross slide 9 in a direction Z through a ball screw 12 to perform work of the printed board 16, a thread part of reverse phase to a thread part screwing the spindle part is formed in an upper part of the ball screw 12. a counter weight 18 screwed to this thread part of reverse phase to negate inertia force of the spindle part is provided.